Device for strapping

ABSTRACT

The invention is related to a strapping device ( 1 ) for the strapping of an object ( 14 ) with a strapping tape ( 5 ). The strapping device ( 1 ) comprises a means of guidance ( 3 ) for guiding a strapping tape ( 5 ), which serves for the purpose of forming a loop of strapping tape ( 5 ) in a waiting position. The formation of the loop takes place independently of the position of the object to be strapped ( 14 ). The strapping device ( 1 ) furthermore comprises a means for movement of the loop ( 4 ). This means serves for positioning the loop of strapping tape ( 5 ) formed by the means of guidance ( 3 ) from the waiting position into a stacking position around an object ( 14 ) to be strapped, after this object has been positioned on a work surface ( 2 ).

[0001] The invention is related to a device for the strapping with astrapping tape of an essentially cube-shaped (cuboid) object, forexample, of a stack of printed products or suchlike.

[0002] Known from prior art are various devices, which serve for thestrapping of stacks of printed products by means of strapping, inparticular of a strapping tape. In the case of these devices, a stack ofprinted products to be strapped is brought to a strapping device by afeeding device, where one or several strapping tapes are laid around thestack. After the strapping, the strapped stack is conducted away fromthe work zone. Utilised as strapping tapes are mostly plastic tapes,e.g., made of polyethyleneterephthalate or polypropylene.

[0003] Strapping means are primarily laid around a stack, resp., arounda cube-shaped (cuboid) device in two directions: In the direction ofconveyance (longitudinal strapping), in which the stack brought into thework zone, and transverse to it (transverse strapping). While thestrapping in transverse direction can be coped with by the devices knownfrom prior art, a strapping in longitudinal direction with the samedevices is in most cases associated with certain problems, because as aresult of the principle involved parts of the machine are arranged in amanner, which makes them liable to interfere with the process.

[0004] From DE 41 00 276 a device is known, which comprises a curved,longitudinally slotted channel, which is arranged at an angle above andadjacent to a stack of printed products to be strapped. A strapping tapeis introduced into the channel, in order to thereupon be laterallypulled out of it. Until the tape finally has been laid around a stack tobe strapped, it first has to slide over an inclined surface and then hasto overcome at an angle a free stretch in the air. This arrangementencompasses certain uncertainties, because as a result of the inclinedtrajectory it is only poorly possible to determine, where the tape willcome to lie.

[0005] From DE 42 30 730 a further device is known, which comprises astatic and a movable tape guide channel. This channel is arranged at anoblique angle to a feeding device. In order to be in a position torationally strap a stack of printed products, it is necessary to alignit at a corresponding angle relative to the channel.

[0006] From EP 0 725 005 a device is known, in the case of which astrapping tape is conveyed across a free stretch of air by means of airpressure. This device has the disadvantage, that a secure conveyance ofthe strapping tape across the free stretch of air is only able to beguaranteed with difficulty. Apart from this, as a result of theprinciple it is only possible to form the tape into a loop after a stackto be strapped has reached a work zone.

[0007] It is the objective of the invention presented here todemonstrate a strapping device, which avoids the disadvantages knownfrom prior art. The device is to make it possible to rapidly strapobjects in longitudinal—and/or in transverse direction in a simplemanner.

[0008] The objective is achieved with the invention defined in theclaims.

[0009] The invention divulged here is in preference suitable for thestrapping of printed products and other objects. These can havediffering dimensions and positions. The invention is in particulardistinguished by a rapid processing and a high flexibility, because theloop can be prepared independent of the position of the stack to bestrapped. Because of only a small number of fast moving parts, anoptimised cycle is achieved. The invention is suitable in particular fora strapping both in longitudinal as well as in transverse direction.

[0010] The invention is based on the fact, that a means of strapping, inparticular a strapping tape, which is to be laid around a stack ofprinted products, is prepared by means of a suitable loop forming devicein a waiting position, independent of and free of (uninfluenced by 90°)the momentary position of the stack to be strapped, i.e., is formed intoa loop. This prepared loop thereupon, as soon as the stack to bestrapped has reached a strapping position, by means of a loop movementdevice by turning (e.g., folding over by) and/or by lateral displacementis brought into a stacking position from the waiting position, in whichit encircles the stack at a certain distance in preference centrally.Subsequently the loop, starting out from the stacking position, is laidaround the stack, tightened and locked so as to form a strapping.

[0011] The invention can be designed in such a manner, e.g., that theloop forming device is a groove embedded in a horizontal work surface,which serves as guide track, resp., guide means for the strappingdevice. Into this groove the means of strapping is introduced, resp.,inserted in longitudinal direction and formed into a loop (loop inwaiting position). In doing so, the groove is designed in such a manner,that the loop does not protrude from the groove and so does not have anobstructive effect. As soon as the stack to be strapped has reached astrapping position, the loop present in the groove in the waitingposition is raised away from the work surface into an upright positionby means of the loop forming device (e.g., by rotation around a point)in such a manner, that the loop comes to lie above and lateral to thestack to be strapped. The loop is now in the stacking position.

[0012] The loop movement device, for example, comprises one or severalstraight or curved arms arranged as fixed or movable, along whichgrippers are located, which can be displaced under control. The grippersare designed in such a manner, that they are in a position to bring themeans of strapping (strapping tape) from the waiting position into thestacking position. For example, the grippers, depending on the field ofapplication, can have an open or closed, single- or multi-partconstruction. In preference they are of lightweight construction, sothat they can be displaced rapidly.

[0013] Particularly suitable as drive for the loop movement means,resp., for the grippers, are recirculating traction elements, airpressure (compressed air), hydraulic systems, solenoid or piezo-electricdrives. The one or more loop movement means advantageously are designedin such a manner, that the movement of the grippers along the arms andthe position of the arms, resp., their relative course, is adjustable.As a result of this, objects of the most differing size (height, width,length and shape) are able to be processed. Because of the flexibledesign, it is possible to influence the loop even while it is broughtfrom the waiting position to the stacking position, in that, forexample, the arms are moved relative to one another. This has the effectof specifically enlarging the loop or of making it smaller. The stackcan assume differing strapping positions.

[0014] In the stacking position, the loop is bigger than thecircumference of the stack to be strapped, in such a manner, that itencircles the latter at a certain distance. Starting out from thestacking position, the loop is separated from the loop movement device,resp., from the one or more grippers and drawn together in such amanner, that the strapping means tightly girdles the stack to bestrapped. Subsequently the means of strapping is tied down and closed toform a strapping.

[0015] A preferred embodiment of the invention is explained in moredetail on the basis of the following Figures.

[0016] These illustrate:

[0017]FIG. 1 a preferred embodiment of a device in accordance with theinvention with a loop of a strapping tape;

[0018]FIG. 2 the device according to FIG. 1 with a stack to be strapped;

[0019]FIG. 3 the device in accordance with FIG. 1 with a strapped stack.

[0020]FIG. 1 schematically and in a strongly simplified way illustratesa strapping device 1 in accordance with the invention. This, i.a.,comprises a work surface 2, a groove 3 embedded in the work surface andtwo loop movement devices 4. The groove 3 embedded in the work surface 2runs essentially along the edges of a rectangle and serves as means ofguidance (guide channel) for guiding a strapping means, resp., thestrapping tape 5. The groove 3 is designed in such a manner, that thestrapping tape 5 can be introduced into it, in that it is pushed into itin the direction of the arrow P either actively or passively from asupply magazine, for example, from a supply roll, which is locatedunderneath the work surface 2. If so required, additional tape feedingmeans (not depicted in more detail), for example, in the form of tapefeed rolls (not depicted in more detail) are present, which assist inthe introduction of the strapping tape 5 into the groove 3. The depth ofthe groove 3 is selected in such a manner, that a strapping tape 5introduced into it does not protrude from the groove 3. Additionalelastic elements (not illustrated in more detail), such as lamella orbristles, close off the groove 3 against the work surface 2 in such amanner, that the strapping tape 5 is secured against inadvertentlycoming out of the groove 3 and that the danger of contamination withdirt of the groove 3 is reduced. The groove 3 can also be closed-offduring the introduction of the strapping tape 5 by means of a rigidelement (not illustrated in more detail).

[0021] Also located underneath the work surface 2 are as such knowntightening—and cutting devices (not depicted in more detail) serving fortightening the strapping tape 5. A closing device 10 serves to tightlyclose the strapping tape 5 to form a ring, which tightly encircles thestack of printed products (refer to FIG. 2). The closing device, forexample is an ultrasonic welding device, which is located in the zone ofthe work surface 2. It goes without saying, that also other devices canbe utilised for closing and cutting off the strapping tape 5.

[0022] In the illustrated embodiment, the two loop movement means 4 eachrespectively comprise one arm 11, which protrudes from the work surface2 in the zone of the groove. The curved arms 11 essentially run parallelto—and extend over the work surface in an arc in such a manner, that astack to be strapped (refer to FIG. 2) can be moved under them or acrossbetween them. Along each one of the arms 11, a gripper 12 is arranged tobe displaceable under control in a guide groove 13. The grippers 12 inthe illustrated waiting position project into the groove 3 and aredesigned in such a manner, that they temporarily take hold of thestrapping tape 5 as soon as it has been introduced into the groove 3 toform a loop, and thereupon are able to raise it away from the worksurface into an upright position.

[0023] The arms 11 can either be arranged to be movable or else can havea variable geometry in such a manner, that their position relative tothe work surface 2, their lateral distance and course can be changed,resp., adapted. As a result of this, it is possible to strap stacks ofthe most differing sizes at different stacking positions. The stacks tobe strapped can be supplied, resp., conveyed away again between the armsor transverse to them. Through the curvature and the course of the armsII, the loop can be influenced in a specific manner while it is beingbrought into the strapping position.

[0024] In the illustrated embodiment, the grippers 12 each respectivelyconsist of a plastic element (e.g., an elastic clip) with an essentiallyU-shaped opening, which serves for the temporary taking hold of thestrapping means 5. These plastic elements are each respectively drivenby a steel string guided within the guide groove 13 (not illustrated inmore detail). Underneath the work surface there is a driving device (notdepicted in more detail), which serves to unroll -and roll up the steelstrings of each arm 11. The arrangement illustrated is characterised,i.a., by the fact, that the mass of the moving parts (gripper 12 andsteel string, resp., loop of strapping tape) is very low and that onlyfew parts have to be moved rapidly. The grippers 12 serve as drivingdevices for the means of strapping 5. Depending of the field ofapplication, instead of the U-shaped opening depicted here, they canalso comprise an opening with an O-shaped, slotted cross section, fromwhich the means of strapping 5 can be pulled out laterally. Otherdesigns are also feasible.

[0025]FIG. 2 in a strongly simplified and schematic manner illustratesthe device in accordance with the invention 1 according to FIG. 1 with astack to be strapped 14 on the work surface 2. This stack is depictedsimplified as a cube-shaped object. The strapping tape 5 in the waitingposition previously formed into a loop in the work surface 2 is locatedin a position raised upright by approx. 90° relative to the work surface2 (stacking position), lateral to and above the stack 14 and at acertain distance from it. The loop of strapping tape has been raisedinto an upright position by the grippers, in that these have been movedalong the arms 11. Starting out from this raised upright position(stacking position), the strapping tape 5 is pulled together in thedirection of the arrows 15, in that it is pulled backwards into thesupply magazine located underneath the work surface 2 (not illustratedin more detail). In doing so, the strapping tape 5 is separated from thegrippers 12. As a result of being pulled together, the tape 5 comes tolie tightly around the stack to be strapped 14 (refer to FIG. 3). Thegrippers 13 are positioned in dependence of the stacking position of thestack 14.

[0026] The grippers 12 can be moved either in synchronicity orasynchronously. As a result of this, it is possible, e.g., to at leastin part bring the loop into an upright position already while the stack14 to be strapped is still in the course of being supplied.

[0027]FIG. 3 illustrates the device in accordance with the FIGS. 1 and 2with a strapped stack 14. The strapping tape 5 has been cut off from theremaining tape and closed to form a ring by means of the closing device10. The grippers 12 are being moved back to their starting positions inthe zone of the work surface 2 in the direction of the arrows 16. Afterthe stack 14 has been conveyed away, the device is in readiness for thestrapping of a further stack of printed products. While the new stack(not depicted in more detail) is being supplied, in the loop guidancemeans the loop is already being prepared for its strapping.

[0028] For the sake of simplicity, the strapping of a stack has onlybeen described in one direction. The invention, however, can also bedesigned in such a manner, that more than one strapping, e.g., in twodirections are possible, inasmuch as correspondingly more loop movementmeans 4 are provided. In the zone of the work surface 2, for example, arotary table can be arranged, which makes possible an additionaldifferent alignment of the stack to be strapped.

[0029] For the specialist it is a matter of course, that the inventionis not solely limited to the embodiment illustrated.

1. Strapping device (1) for the strapping of an object (14) with a meansof strapping (5), characterised in that the strapping device (1)comprises a means of guidance (3) for guiding the strapping means (5),which means of guidance (3) serves for the formation of a loop of meansof strapping (5) in a waiting position, independent of the position ofthe object to be strapped (14), and that a loop movement means (4) ispresent, which serves to position the loop of strapping means (5) formedby the means of guidance (3) from the waiting position in a stackingposition around an object to be strapped (14).
 2. Strapping device (1)in accordance with claim 1, characterised in that the means of guidance(3) is a groove (3) embedded in a work surface (2), in which the meansof strapping (5) is able to be pushed in, and that the loop movementdevice (4) comprises at least one arm (1) projecting from the worksurface (2) with at least one gripper (12), which is arranged to bedisplaceable under control along the at least one arm (11) and whichserves as driving means for moving the loop of strapping means (5) fromthe waiting position into the stacking position.
 3. Strapping device (1)according to claim 2, characterised in that the at least one arm (11) iscurved.
 4. Strapping device (1) in accordance with claim 2 or 3,characterised in that the at least one arm (11) is arranged to bemovable relative to the work surface (2).
 5. Strapping device (1)according to one of the claims 2 to 4, characterised in that the atleast one gripper (12) comprises an opening with a substantiallyU-shaped or O-shaped, laterally slotted cross section, which serves forthe temporary taking hold of and moving of the means of strapping (5)and which is designed in such a manner, that it can release the means ofstrapping (5) in a stacking position.
 6. Strapping device (1) inaccordance with one of the claims 2 to 5, characterised in that in theinterior of the arm (11) a movable, driven wire string is arranged,which is connected with the at least one gripper (12) and which servesfor driving it.
 7. Strapping device (1) according to one of the claims 2to 6, characterised in that the strapping device (1) comprises at leastone electric motor and/or one compressed air motor and/or one hydraulicmotor and/or one solenoid motor and/or one piezo-electric motor, whichserves or which serve for driving the at least one gripper (12). 8.Strapping device (1) in accordance with one of the claims 2 to 7,characterised in that the strapping device (1) comprises precisely twoarms (11) each respectively with one gripper arranged to be controllablymovable along it.
 9. Strapping device (1) according to one of the claims2 to 8, characterised in that the means of guidance (3) extendsessentially along the edges of a rectangle.
 10. Strapping device (1) inaccordance with one of the claims 2 to 9, characterised in that thegroove (3) is closed off by means of elastic elements.